Actuating mechanism for tension lockup printing plate cylinders



Aug. 24, 1965 F. .1. DoYLE ETAL 3,202,097

ACTUATING MECHANISM FOR TENSION LOOKUP PRINTING PLATE CYLINDERS 5 Sheets-Sheet l Filed sept. 4, 1963 CATTQRMEYJ" Aug' 24 1965 F. J. DOYLE ETAL ACTUATING MECHANISM FOR TENSION LOCKUP Flled sept 4 1963 PRINTING PLATE CYLINDERS 5 sheets-sheet 2 s Jmus J. DLEOR CH utk 00% QM Choddk Ala/M @34M @T1-ORNE Vw CTUATING'MECHANISM FOR TENSION LOCKUP Filed sept. 4, 1965 PRINTING PLATE CYLINDERS 5 sheets-sheet s -fe i i 1 l l l l I I 1 e 1 i L* I l x l C INVENTORS Minnow @wiwi F. J. DOYLE ETAL Aug 24 ACTUATING MECHANISM FOR TENSION LOCKUP PRINTING PLATE CYLINDERS Filed Sept. 4, 1963 5 Sheets-Sheet 4 INVENTORS 3FG YK CI Dqle Cor @hf-10H l ChucLJLi n wuwfw, mh am v @Tremor-:yf

Al1g- 24, 1955 F. J. DOYLE ETAL ACTUATING MECHANISM FOR TENSION LOOKUP PRINTING PLATE CYLINDERS 5 Sheets-Sheet 5 Filed Sept. 4, 1963 vESNTOM/ J-ravugd DQLSG Cvz, 0 Cluud LJ@ 00%/ l, Cada/vvd PHTToRNElY-f United States Patent 3,202,097 ACUATHG ll/lECHANlSM FR TENSEON LOCKUP PRlN'l'lNG PLATE CYLHNDERS Frank ll. Doyle, Bellwood, and Anthony Chudzir, Cicero, lll., assignors to Miehle-Goss-Dexter, Incorporated,

Chicago, Ill., a corporation oi' Delaware Filed Sept. d, 1963, Ser. No. 305,447 l Claims. (Cl. lill-378) The present invention relates in general to plate cylinders for printing presses, and in particular to the mechanism by which the movable, spring-biased fingers which hold printing plates on the cylinder surface are selectively moved between plate locking and unlocking positions.

In the past several years there has been `an almost universal adoption of the so-called tension lookup system of holding stereotype printing plates on the plate cylinders of newspaper presses and those of similar nature. Generally stated, the half or quarter cylinder printing plates cast from type metal are milled to have undercut pockets at their opposite axial edges. When such a plate is applied to a cylinder, the pockets along one edge receive rigid holding hooks (which are adjustable in position to register the plate, and are thus called registering hooks), while the pockets in the opposite edge of the plate are releasably engaged by movable tension fingers. These tension fingers are actuatable or movable between an unlocking position (retracted beneath the cylinder surface) and a locking position. As the plate is being locked up, the tension fingers are moved in unison until they seat firmly Within the plate pockets, and are further stressed against resilient or spring means until they exert a yieldable force on the plate to tension the latter in a direction circumferential of the cylinder.

The spring forces exerted by the tensioning fingers are relatively high, and the sum of forces exerted by all the tensioningr fingers for two or more side-by-side plates aggregates to an effort which is beyond the strength of a Pressman to directly overcome. lt is, therefore, necessary that some force-multiplying mechanism with a relatively high mechanical advantage be interposed between the tension fingers and the element which is manipulated by an operator to lock or unlock the plates. That demand is, however, complicated by the facts that a high mechanical advantage results in a low ratio of displacements of the tension fingers and the manipulated element, and that the lingers must be moved over a relatively wide range. Yet, it is only the last portion of the locking-up motion and the first portion of the unlocking motion which occurs with heavy spring forces on the tension lingers and plate. While a variety of tension finger actuating mechanisms have been previously employed on tension lock up cylinders, they have as a general rule involved either high mechanical advantages so that ext-ended hand induced motion was required, or bulky and complex mechanisms, many of which required power means (such as pneumatic cylinders) to effect the locking or unlocking movement of the tension fingers.

It is the general aim of the present invention to provide a new and improved mechanism for actuating the tension fingers of a tension lock up cylinder for printing plates.

lt is a related object to provide such an actuating mechanism which acts with a changing mechanical advantage as a printing plate is being locked up or released, and particularly so that the mechanical advantage is `high (and the displacement ratio low) when large spring forces are present, yet'so that the mechanical advantage is low (and the displacement ratio high) when the spring forces are absent or negligible.

More particularly, it is an object of the invention to provide such an actuating mechanism which does not function merely in a two-Way reversible manner, but on the Aice contrary, which acts with a mechanical advantage that increases in a first manner as the tension fingers are being engaged and stressed, yet, with a mechanical advantage which changes and decreases in a different, second manner as the tension lingers are being relieved and Withdrawn from the plate pockets.

Another object of the invention is to provide such a linger-actuating mechanism which affords movement of a finger shaft from an unlocking position. to a locking position by manual turning of a lever in a plane disposed radially of the cylinder, and through a relatively small angle on the order of degrees.

Still another object of the invention is to facilitate the releasable retention of the mechanism and lingers in their unlocking positions, despite the fact that the mechanism is spontaneously reversible. ln this connection, it is an object to retain an actuating mechanism in its unlocked condition by employing a removably insertable hand lever e as a part of a releasable latch.

A further and important object is to accomplish the foregoing by a mechanism which is very compact and yet simple and rugged in its organization and construction. i 1

Gther objects and advantages will become apparent as the following description proceeds, taken in conjunction with the accompanying drawings, in which FIGURE l is an end view, partially in section, of a tension lock up cylinder equipped with an actuating mechanism embodying the features of the present invention;

FlG. 2 is similar to FIG. l, but shows the left portion of the cylinder with the mounting bracket removed, and the right portion of the cylinder in section to reveal the nger shaft and one tension finger;

FlG. 3 is a fragmentary elevation, taken generally along the line 3 3 in FIG. l, of the end portion of the cylinder which mounts the actuating mechanism;

FlG. i is a detail view showing the assembled hub and link employed in the actuating mechanism;

FlGS. 5 and 6 are detail views individually showing the hub and link, respectively; and

FlGS. 7-11 are stop motion views (FIG. 8 being in perspective) illustrating the relative positions of component parts as they are moved progressively between 4plate unlocking and plate locking positions.

While the invention has been shown and will be described in some detail with reference to a particular-ernbodiment thereof, there is no intention that it thus be limited to such detail. On the contrary, it is intended here to cover all modifications, alterations, and equivalents falling within the spirit and scope of the invention as derined by the appended claims.

Referring now to FIGS. 13, a plate cylinder l2 is there shown as mounting two semi-cylindrical printing plates ld which conventionally are cast of type metal and machined to have pockets )l5 and i6 in the undersides of their trailing and leading edges. Because the general organization and operation of tensioning plate cylinders are well `known to those skilled in the art, they will not here be described in detail. One example is fully illustrated and described in US. Patent 2,639,668 issued in the name of Corson Walter Chase et al. lt will suflice here to note only that the cylinder l2 is symmetrical in cross- `section and mounts two identical sets of tension finger and register hook mechanisms for the two respective plates ld. Accordingly, a description of one set of the tensioning and registering components will suflice for both.

When the printing plate 14 is mounted on. the cylinder, its pockets l5 receive register hooks 18 which project slightly above the cylinder surface. These hooks are rigid and thus serve to anchor the trailing edge of the plate against the circumferential pull or tension exerted n i by tensioning fingers 19 which engage in the pockets 16 at the leading plate edge. The registering hooks 18 (several of which may be spaced lengthwise of the plate) are, however, adjustable in position by a suitable registering mechanism in order to afford adjustment and determination of the position of the plate 14 relative to the cylinder surface. Because the registering mechanism forms no essential part of the present invention, it will not be described, but the reader may refer to the abovementioned Chase et al. patent if details are desired.

In order to exert substantial tension on the plate 14 in a direction circumferential of the cylinder 12, and yet to permit the plate to be readily removed and replaced, the tension fingers 19 are so arranged that (a) they may be moved between locking or unlocking positions in which they respectively reside above or below the cylinder surface, and (b) they engage in the pockets 16 and have a strong resilient bias applied thereto as the actuating mechanism reaches its final plate-locking position. While any one of a variety of specic tension hook and biasing arrangements may be employed, the one here illustrated is similar to that shown in the above-mentioned Chase et al. patent. It includes a finger shaft 21 disposed longitudinally in the body of the cylinder 12 and journaled for rotation between two angular positions, i.e., a plate unlocking position and a plate locking position (compare the left and right portions of FIG. 1). It will be understood that a plurality of the tension hooks 19 are spaced axially along the cylinder, each being formed as an integral part of a finger piece 22 (FIG. 2) pivoted at 24 to the shaft 21. Preloaded compression springs disposed in bores 26 formed transversely in the shaft 21 resiliently 'urge each finger piece 22 in a counterclockwise direction to a limit position relative to the shaft. When the finger shaft 21 is rotated fully to its unlocking position (left portion of FIGS. 1 and 2), plate lifting ears 28 formed as an integral portion of the finger shaft 21 abut the edge of the plate 14 and lift it slightly away from the surface of the cylinder. This facilitates grasping and lifting the plate away from the cylinder when it is to be removed.

When a plate is to be locked up, it is positioned as shown by the plate 14 in the left portion of FIG. 2, and the finger shaft 21 is then rotated in a counterclockwise direction. As this shaft rotates, the finger pieces 22 first move bodily therewith so that the tension hooks 19 move up from beneath the surface of the cylinder and into the plate pockets 15. As rotation ofthe finger shaft continues, the tips of the tensioning fingers 19 cannot move appreciably further since they are in engagement with the surfaces of the pockets 16. Rather, the finger pieces 22 rock about their pivot points 24 as the shaft 21 continues to turn, so that the preloaded springs 25 are further cornpressed. Thus, the springs exert a continuous and strong force through the tensioning fingers 19 which pulls the plate 14 circumferentially against the anchoring action of the register hooks 13, thereby holding the plate rmly locked on the cylinder surface. While the finger shaft 21 moves through an angle of approximately 35 degrees between unlocking and locking positions, the action of the compression springs 25 begins and continues over only a relatively small angle of movement of the shaft just at the end of the locking up motion.

In accordance with one aspect of the present invention, provision is made to rotate the finger shaft 21 between locking and unlocking positions simply by manual movement of a straight lever in a plane which is disposed substantially radially of the cylinder. For this purpose, a hub is mounted on the cylinder 12 and journaled for rotation in a plane radial of the cylinder, i.e., for rotation about an axis which is parallel to the cylinder axis. The bodyvof the hub 3f) is formed to define a socket 31 adapted to receive one end of an insertable lever 32 which permits an operator or pressman to manually rotate the hub 3f) between first and second rotational positions.

As here shown, the hub 30 is formed with oppositely fr extending trunnions 34 one of which is received in a bearing recess 35 formed in the cylinder body, and the other of which is received and iournaled by a bracket 35 bolted to the end surface of the cylinder 12 (FIG. 3). As best shown in FiG. 3, the cylinder 12 has its shaft 38 received and ,iournaled in a supporting press frame 39, the bracket 36 and the tension lock up mechanism being disposed in the relatively narrow space between the body of the cylinder 12 and the frame.

It is a relatively simple matter for an operator to insert the removable lever 32 into the socket 31 of the hub 3d and then manually to swing the lever in order to rotate the hub between a first rotational position (see the left side of FIG.' 1 or FiG. 7) and a second rotational position (see the right side of FIG. l or FIG. ll). As will become apparent hereinafter, the lever 32 and the hub 30 are rocked through an angle of approximately 95 degrees in order to move the hub between its first and second positions, and to correspondingly move the finger shaft 21 between its plate unlocking and locking positions.

The hub Sii is mechanically connected to the finger shaft 21 by a mechanism which includes as its major parts a link dii and a radial arm 41, the latter being splined to and extending radially from the finger shaft 21. One end of the link ifi is pivotally connected to the radial arm 41 by a pin 42 so that movement of the link ifi correspondingly rocks the finger shaft 21.

ln keeping with an important `feature of the invention, means are provided between the hub 3l) and the finger shaft 21 to shift the latter toward its locking position with an increasing mechanical advantage as the hub 3@ is turned from its first to its second position. In addition, a second means, which is constituted principally by the same elements, is provided to shift the finger shaft 21 from its locking to its unlocking position with a decreasing mechanical advantage as the hub is turned from its second to its first position. The particular mechanical advantages and the way in which they change during locking and unlocking movements are, however, somewhat different in those two cases.

For this purpose, the hub 3@ is formed with two spaced fianges 4d (FlG. 4) having alined openings 45 formed therein. These flanges are spaced apart to receive therebetween that end of the link d@ which is opposite the end connected to the radial arm 41 and a iioating pivot connection is established between the two parts. As shown best in FIGS. 4 and 6, the link 4d has two holes 46, 47 drilled therein to receive two transverse pins d8 and 49 of circular cross-section, the holes communicating with channels 47a which transmits a lubricant thereto. The opposite ends of the pins d8, #i9 project into the openings 4S formed in the two fianges i4 of the hub Sil.

lt will be observed that in the exemplary embodiment, the pin 4d is somewhat larger in diameter than the pin 49, this being possible because the smaller pin is required to transmit forces considerably less than those transmitted vby the larger pin. The openings 4S in the hub flanges are larger in cross-sectional area than the combined crosssectional areas of the two pins 43, 49, and are shaped especially to accommodate and coact with these pins. t will be understood, however, that if two pins of the same size are chosen, then the shape of the opening would be modified from that here shown.

Referring now to FIG. 5, each hub opening 45 is formed such that its periphery defines first and second substantially semi-circular seats Sti and 51 which have radii substantially equal to those of the respective pins ES and 49. Extending from the first seat Sii is an arcuate surface portion 52 which is struck on the radius 54 about the center 55 of the second seat S1. Similarly, a second arcuate surface portion 56 extends from the second seat S1, being struck on a radius 58 about the center 59 of the first seat 50. The centers of the holes i6 and 4'7 (FlG. 6) in the link 4t), and thus the centers of the pins 4S and 49 insorted therethrough, are spaced apart by a distance d which equals the distance between the centers- S9 and 55 of the semi-cylindrical seats 5t? and 51 in the opening 45 (FIG. 5). Thus, the pins 48 and 49 are fixed in their relative spacing, but can shift somewhat relative to the peripheral wall of the opening 45, with both pins d8 and 49 residing simultaneously in their respective seats 50 and 51 when the link Lttl and the hub 30 are in a predetermined angular relationship, as shown particularly in FIG. 9.

A narrative of the sequence of events which occurs during the locking up of printing plate and during the unlocking of a plate, with reference to stop-motion views in FIGS. 7-11, will best describe the operation and advantages of this compact tension finger actuating mechanism. Assume that the hub 30 is in its first position, and the hook shaft 2l is in its unlocking position (FIG. 7), so that the tension lingers 19 are retracted below the cylinder surface (as shown in the left portion of FIG. 2). The operator in applying a new plate I4 to the cylinder will slip the trailing edge of the plate over the register hooks ,'18, and lower the plate into the position shown at the left in FIG. l. The lever 32, previously inserted into the socket 31 of the hub 3th, is then grasped and pulled downwardly (counterclockwise as seen in FIG. l). As the hub Sil thus turns on its trunnions 3d, it applies a force to the large pin 43, and therefore shifts the link 4) and the arm 41 in a direction to rotate the finger shaft 21 toward its locking position. The small pin i9 does not contribute to this force transmission. Since the large pin 43 is now disposed at a relatively large distance Rl (FIG. 7) from lthe rotational :axis titl of the hub 3), the latter acts with a relatively low mechanical advantage and a high displacement ratio on the Ilink 40.

` As the rotation of the hub begins and continues from t-he position shown in FIG. 7 `to that `shown in FIG. 8, the large pin 48 rides downwardly and inwardly on the arcuate `surface portion 52 of the opening 45. Force continues to be transmitted from the lever 32 ythrough the hub Sil to the link fill through the large pin 48, but the smaller pin residing in its seat 5l, forces the link 4d to rotate relative to the hub iianges. The distance from the rotational axis 60 of the hub to the center of the pin 43 thus progressively decreases, so that the mechanical advantage of the mechanism increases and the displacement ratio decreases. It is during this range of movement that the shaft 2l and the tension ngers 19 are rotated through a relatively large portion of their travel toward initial engagement with the plate pockets I6.

By the time that the hub has been turned to the position shown in FIG. 9, the large pin 4S has moved over the arcuate surface portion 52 and into its semi-cylindrical seat 5t). Thus, the mechanical advantage of the force transmission between the hub Sil and the link 4% has increased to its highest value, the effective radial distance from the hub axis 60 to the center of the pin having been reduced to the value R2. It is at ythis point that the iingers 19 have been brought approximately into initial engagement with the pockets 16 of the plate I4. Thus, during the initial movement of the hub 30, the mechanism acts with a relatively low but increasing mechanical advantage.

As the rotation of the hub 30 is continued from the angular position illustrated in FIG. 9 to the angular position illustrated in FIG. l0, force continues to be transmitted from the hub to the link through the large pin 48, the link servingptherefore, to continue the rotation of the radial arm 4l and the linger shaft 2l. During this travel, the large pin 48 remains in the seat 5t?, Vbut actswith a progressively increasing mechanical advantage by virtue of the facts that the hub 3i) and link 4l) form a toggle linkage having three centers at the axes 34, #t8 and 42,

p respectively, and that the toggle linkage is approaching a dead center position. It will be noted that the triangle (FIGS. 9 and 10) on which the three toggle centers lie progressively narrows as the parts move from the positions of FIG. 9 to those of FIG. l0. However, during this interval of motion, the small pin 49 and the hub opening 45 are both moving counterclockwise about the axis 6i), but pin moves more slowly so that it begins to move out of its seat 5l and to advance along the arcuate surface portion 5o. By the time that the hub is rotated fully to its second position (FIG. l1) the small pin 49 has shifted, relative to the opening 45, completely over the arcuate surface portion 56 and almost into engagement with the surface portion 52. It is during the motion illustrated by FIGS. 9, l0 and ll that the finger pieces 2?; (FIG. 2) with their fingers I9 having engaged the pockets 16, are rocked about their pivot points 24 to compress the springs 25 and thus to exert a strong resilient force against the pockets lo to hold the plate I4 on the cylinder.

Just before the hub 30 reaches the position shown in FIG. ll the springs 25 have been considerably compressed, and the force on the linger shaft 2l to produce this compression of those springs is of considerable magnitude. It is at this instant of maximum spring compression that the three centers of the toggle mechanism approach alinement or dead center relation, thereby producing the maximum mechanical advantage. Thus, the mechanism provides the maximum advantage when the maximum force is necessary to compress the springs 25. This comes about because (l) the large pin di; is located at the small radius R2 from the axis 60, and (2) the toggle centers approach dead center alinement and the toggle arrangement produces its highest mechanical advantage.

When the finger shaft 2l is moved to its locking position, it must necessarily be retained there during subsequent rotation of the cylinder and printing operations. For this purpose, a cross pin is extended between the flanges d4 of the hub 3@ and so located that it will abut the edge of the link itl when the mechanism is slightly That is, since the` over center as shown in FIG. 1l. center of the pin d8 is turned to a location slightly past a line connecting the axis 60 and the center of the pin 42, the clockwise torquev exerted on the finger shaft 2l and the radial arm l bythe compressed springs 25 holds the pin 65' firmly abutted against the link riti, and the parts are securely retained as a result of this biasing force on the over centered mechanism. Thus, after the parts have been locked up in the manner described, it is a simple matter for the operator to withdraw the lever 32 from the socket 3l of the hub, and to put the printing cylinder and the press with which it is associated into operation.

When a printing run has been completed and it is desired to remove the printing plate I4 from the cylinder, the operator need only reinsert the lever 32 into the socket of the hub Ell. He then turns the lever 32 and the hub 3i? in a clockwise direction (as viewed in FIG. 11) so as to swing the large pin t8 from its over center position. This requires an aiiirmative force on the part of the operator, but once the pin 48 has been retracted beyond its over centered position, then the biasing force of the compressed springs 25 tends to continue the movement of the arm 4I, the link 40 and the hub Sil. Thus `the operator applies a cushioning and restraining force to the lever and gradually lets the parts return from the position shown in FIG. ll to the position shown in FIG. l0, and thence to the position shown in FIG. 9. Because there is a force transmitting connection between the link iti and the hub Sti through the pin 48 which is now disposed at a relatively small distance R2 from the axis tid, the mechanism acts with relatively high mechanical advantage so that only a relatively small restraining force need be exerted by the operator on the lever 32.

By the time the parts reach the 'position shown in FIG. 9, the springs 2,5 have been decompressed to their maximum extent and the linger piece 22 has been rotated relativo to the shaft 2l to a limit or stop position. The tension fingers I9 thus reside in the plate pockets 16 but are not exerting `an appreciable force against the walls of those pockets. The operator now continues to move the lever 32 and the hub 30 in a clockwise direction from the position shown in FIG. 9 toward the position shown in FIG. 8. As he does so, force and motion are not transmitted from the hub 3@ through the pin 48 to the link isti, but on the contrary, are transmitted from the hub Sil through the small pin 49 to the link titl, inasmuch as the latter is now located in its seat 5l. Because the pin 49 has its center located at a considerably greater distance from the axis 6) of the hub, there is a relatively low mechanical advantage and a high displacement ratio, so that the radial arm 41, the finger shaft 2l, and the tension lingers 19 are rapidly and easily moved toward a position free of the plate pockets and beneath the cylinder surface. During this motion of the hub 30, the large pin 48 moves out of its seat 5&3 and along the arcuate surface portion S2. By the time the hub 3@ has reached the position shown in FIG. 7 (and at the left in FIG. l) the large pin 48 has returned to the end of the arcuate surface portion 52, and all of the parts are in their original positions ready for lock up on the next printing plate.

It will thus be seen that this mechanism, While very simple and compact, acts differently when it is being employed to lock up a printing plate than when it is being employed to unlock a printing plate. During locking up operation, the mechanical advantage starts at a relatively low value and is changed in an increasing direction, reaching its maximum value when the greatest force is required to compress the springs associated with the tension fingers. On the other hand, during unlocking movement of the mechanism, it acts initially with a relatively high mechanical advantage through the large pin 48 during that motion when compression of the springs is being relieved, but thereafter the mechanical advantage is changed in a decreasing direction, and in a manner different from that which occurred during lock up, by virtue of the fact that the effective connection between the hub and the link is transferred to the small pin 49. The small pin 49 produces a quick return action since it acts with a relatively low mechanical advantage and high displacement ratio.

Whenever the printing press has been stopped to change the plates on a cylinder, it is desirable afirmatively to hold the tension fingers and the actuating mechanism in their released or unlocking positions. The mechanism herein described is susceptible of spontaneous movement in a locking direction, for example, if the ears 28, projecting above the cylinder surface, should be struck by the edge of a plate being lowered into the position illustrated at the left in FIG. l. Thus, it might be necessary to manually return the lever 32 to the unlocking position and hold it there in order to locate the plate in place before locking it up.-

In accordance with another aspect of the invention, provision is made to releasably restrain the hub 3f), and thus the finger shaft 21, in the unlocking positions, by an arrangement which prevents removal of the lever 32 so that its presence apprises and reminds an operator that the plate is still unlocked. To accomplish this, a releasable latch is constituted in part by the lever 32 itself.

In the exemplary embodiment here illustrated, the lever 32 is constructed to include a radial projection in the form of a ange 79 which is movable between first and second positions axially along the lever. More specifically, the flange 70 is formed at the lower end of a sleeve 71 which is slidable along the shank 72 of the lever, a handle portion 74 of the lever being threaded at 75 into the uprigidly carried by the cylinder in a position adjacent the hub and located to receive the lever as it is moved to unlocking position. As here shown, one end of the bracket is shaped to include an overhanging latch plate S1 having a keyhole shaped cutout 82 formed therein. The entrance slot 34 of this cutout is oversized with respect to the diameter of the lever sleeve 71, while the circular portion 35 of the cutout is sized to receive the flange 70 as it moves upwardly from beneath the latch plate.

As the operator moves the lever 32 to its fully unlocked position, he depresses the handle portion 74 so that the flange is shifted toward the socketed end of the lever. Accordingly, the flange 70 passes under the latch plate 81, and the sleeve passes through the entrance slot 34. When the lever handle 74 is released, the compression spring 76 lifts the flange 7@ upwardly into the circular portion of the cutout S2 in the latch plate. Thus, the hub 30 cannot rotate from its first or unlocking position. In this manner, the tension fingers 19 and the linger shaft Z1 are afiirmatively latched in their unlocking position as shown by the left portion of FIG. l so that even if in the course of applying the plate 14 to the cylinder surface its edge should strike the lifting ears 28, the parts will remain in their unlocking positions.

After a plate has been applied to the cylinder as shown in the left portion of FIG. 1, it is a simple matter for the operator to release the latching engagement of the lever 32 in the latch plate 81. He need only press inwardly on the handle portion 74 of the lever, thus depressing the flange 70 out of the circular opening S5, and then pull the lever 32 in a counterclockwise direction to shift the tension lingers 19 into locking engagement with the pocket 16 of the plate 14. Once the hub has been turned fully to its second or locking position (FIG. ll) the operator may withdraw the lever from the hub socket 31, and the locked up plate is ready for the printing run.

The exemplary embodiment of the tension finger actuating mechanism is thus seen to be one which is extremely compact, occupying a very small space between the end of the cylinder body and an adjacent press frame (FIG. 3). Yet, in this compact structure, provision is made to effect locking or unlocking action in response to manual movement of a removable hand lever with changing mechanical advantages, so that the high forces required during compression or relaxation of the tensioning springs are easily created by the pressman, and so that the total range of motion for the tension hooks is produced in response to only about degrees of motion of the lever. Once the mechanism has been moved to its plate unlocking position, the arrangement of thehub and lever serves further to releasably latch the parts until they are afiirmatively unlatched by an axial depression of the lever handle.

We claim as our invention:

1. In a tension lockup cylinder having a longitudinally disposed finger shaft journaled therein for rotation between plate unlocking and locking positions and carrying fingers resiliently biased for engaging and tensioning a printing plate when in the locking position, the combination comprising a hub journaled on the cylinder for rotation between first and second angular positions in a plane radial of the cylinder, a radial arm rigid with the finger shaft, a link pivotally connected at one end thereof to said arm, a floating pivot connection between the other end of said link and said hub, means defining a socket in said hub, a hand lever having one end removably insertable into said socket for effecting rotation of said hub, said floating pivot connection including first and second transverse pins carried by said link, means on said hub for forcing the first pin and link to shift said arm and shaft toward their locking positions with an increasing mechanical advantage as said lever rotates said hub from its first toward its second position, and further including means on said hub for successively forcing said first and second pins and said link to 'shift i said arm and shaft toward a decreasing mechanical advantage as said lever rotates j their unlocking positions with lever as the hub is moved to or from its first position,

and said recess beinn shaped to hold and retain said projection when the latter is in a second axial position on said lever and the hub is in its first position, so that said hub is releasably held in its first position and said finger shaft is releasably held in its unlocking position.`

2. ln a tension lookup cylinder having a longitudinally disposed finger shaft journaled therein for rotation between plate unlocking and locking positions and carrying resiliently biased fingers for engaging and tensioning a printing plate when in the locking position, the combination comprising a hub carried on one end of the cyl* inder and journaled thereon for rotation between first and second angular positions in a plane rad-iai of the cylinder, a socket defined in said hub, a hand lever insertable into said socket to effect rotation of said hub selectively between its first and second positions, a radial arm rigid with the finger shaft, a link pivotally connected at one end thereof to said arm, a transverse opening defined in said hub, first and second cylindrical pins carried by the other end of said link and disposed in said opening, said opening being larger than the co1nbined cross-sectional area of said two pins and having its periphery shaped to define rst and second substan- `tially semi-circular seats with first and second arcuate surface portions respectively extending` from such seats and struck about the center of the opposite seat, said two pins and transverse opening constituting means for shifting said link, arm and shaft toward their locking posi-` tions with an increasing mechanical advantage as said hub is rotated from its first toward its second position and said first pin rides along said first arcuate portion into said first seat and said second pin rides out of said second seat and along said second arcuate portion, and

. further constituting means for shifting said link, arm

and shaft toward their unlocking positions with a decreasing mechanical advantage as said hub is rotated :from its second toward its first position and said second pin rides along said second arcuate portion into said second seat and said first pin rides out of said first seat and along said first arcuate portion, said lever including a sleeve axially slidable thereon and having a radialV ange on the ends thereof adjacent said one end of said lever, means for axially biasing said sleeve to a V limit position away from said one end of said lever,

and a latching plate rigid with said cylinder and adjacent said hub, said latching plate being shaped to define a keyhole passage therein and being located to receive said flange as the lever moves said hub to its first position with the sleeve depressed against the force of said biasing means, release of said sleeve then causing said flange to rise into said keyhole slot to retain the hub in its first position.

3. In` a tension lockup cylinder having a longitudinally disposed linger shaft journaled therein and carrying l@ resiliently biased fingers for engaging and disengaging a printing plate when the shaft is rotated between locking and unlocking positions, the `combinationcompris ing a hub journaled on one end of the cylinder for rotation between first and second angular positions in a plane radial of the cylinder, a radial arm rigid with one end of the finger shaft, a link having one end pivotallyV connected to said arm, and a floating pivot connection between the other end of said link and said hub, said iioating pivot connection including first and second transverse pins carried by said link, means on said hub for forcing the first pin and link to shift said arm and shaft toward their locking positions with an increasing mechanical advantage as said hub is rotated from its first `toward its second position, and means on said hub for successively forcing said first and second pins and said link to shift said arm and shaft toward their unlocking positions with successively decreased mechanical advantages as said hub is rotated from its second toward its first position. j i Y d. In a tension lockup cylinder having a longitudinally disposed finger shaft journaled therein for rotation between plate unlocking and locking positions and carrying resiliently biased fingers for engaging and tensioning a printing Plate when in the locking position, the combination comprising a hub carried on one` end of the cylinder and journaled thereon for rotation between first and second angular positions in a plane radial of the cylend thereof to said arm, a transverse opening defined in said hub, first and second cylindrical pins carried by the other end of said link and disposed in said opening, said opening being larger than theconibined crosssectional area of said two pins `and having its periphery shaped to define first and second substantially semicircular seats with first and second arcuate surface portions respectively extending from such seats and struck about the center of the opposite seat, said two pins and transverse opening constituting means for shifting said link, arm and shaft toward their locking positions with an increasing mechanical advantage as said hub is rotated from its first toward its second position and said first pin rides along said first arcuate portion into said first seat and said second pin rides out of said second seat and along said second arcuate portion, and further constituting means for shifting said link, arm and shaft toward their unlocking positions with a decreasing mechanical advantage as said hub is rotated from its second toward its first position and said second pin rides along said second arcuate portion into said second seat and said first pin rides out of said first seat and along said first arcuate portion.

FOREIGN PATENTS 1,092,035 l l/ 60 Germany. EUGENE R. CAPOZIO, Primary Examiner. 

1. IN A TENSION LOCK-UP CYLINDER HAVING A LONGITUDINALLY DISPOSED FINGER SHAFT JOURNALED THEREIN FOR ROTATION BETWEEN PLATE UNLOCKING AND LOCKING POSITIONS AND CARRYING FINGERS RESILIENTLY BIASED FOR ENGAGING AND TENSIONING A PRINTING PLATE WHEN IN THE LOCKING POSITION, THE COMBINATION COMPRISING A HUB JOURNALED ON THE CYLINDER FOR ROTATION BETWEEN FIRST AND SECOND ANGULAR POSITIONS IN A PLANE RADIAL OF THE CYLINDER, A RADIAL ARM RIGID WITH THE FINGER SHAFT, A LINK PIVOTALLY CONNECTED AT ONE END THEREOF TO SAID ARM, A FLOATING PIVOT CONNECTION BETWEEN THE OTHER END OF SAID LINK AND SAID HUB, MEANS DEFINING A SOCKET IN SAID HUB, A HAND LEVER HAVING ONE ND REMOVABLY INSERTABLE INTO SAID SOCKET FOR EFFECTING ROTATION OF SAID HUB, SAID FLOATING PIVOT CONNECTION INCLUDING FIRST AND SECOND TRANSVERSE PINS CARRIED BY SAID LINK, MEANS ON SAID HUB FOR FORCING THE FIRST PIN AND LINK TO SHIFT SAID ARM AND SHAFT TOWARD THEIR LOCKING POSITIONS WITH AN INCREASING MECHANICAL ADVANTAGE AS SAID LEVER ROTATES SAID HUB FROM ITS FIRST TOWARD ITS SECOND POSITION, AND FURTHER INCLUDING MEANS ON SAID HUB FOR SUCCESSIVELY 